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Results for “Morphological Characterization”

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At least 73 records · Page 4Linked to original sources

PubMed2005

Electrophysiological and morphological characterization of dentate astrocytes in the hippocampus.

We studied electrophysiological and morphological properties of astrocytes in the dentate gyrus of the rat hippocampus in slices. Intracellular application of Lucifer yellow revealed two types of morphology: one with a long process extruding from the cell body, and the other with numerous short processes surrounding the cell body. Their electrophysiological properties were either passive, that is, no detectable voltage-dependent conductance, or complex, with Na+/K+ currents similar to those reported in the Ammon's horn astrocytes. We did not find any morphological correlate to the types of electrophysiological profile or dye coupling. Chelation of cytoplasmic calcium ([Ca2+]i) by BAPTA increased the incidence of detecting a low Na+) conductance and transient outward K+ currents. However, an inwardly rectifying K+ current (Kir), a hallmark of differentiated CA1/3 astrocytes, was not a representative K+-current in the complex dentate astrocytes, suggesting that these astrocytes could retain an immature form of K-currents. Dentate astrocytes may possess a distinct current profile that is different from those in CA1/3 Ammon's horn.

Animals↗

PubMed1994

Desbuquois syndrome: clinical, radiographic, and morphologic characterization.

To further characterize the clinical, radiographic and chondro-osseous morphologic changes in the Desbuquois syndrome, 7 patients from three sibships are described. They all had prenatal onset severe rhizomelic and mesomelic shortness with marked joint laxity and marked micrognathia. Radiographic changes were distinct, consisting of a supernumerary ossification center between the proximal phalanx of the index finger and the second metacarpal, and variable thumb changes. The femoral necks showed enlargement of the lesser trochanter with metaphyseal breaking, producing a characteristic "monkey wrench" (Swedish key) appearance. Growth plate cartilage showed dilated cisterns of rough endoplasmic reticulum in reserve zone chondrocytes. Three of the 7 cases were diagnosed prenatally by second trimester ultrasound and one case by fetoscopy. This syndrome exhibits significant phenotypic variability and must be differentiated from the Catel-Manzke syndrome which exhibits similar radiographic changes in the hands.

Adolescent↗

PubMed2006

Morphological characterization of the anuran integument of the Proceratophrys and Odontophrynus genera (Amphibia, Anuran, Leptodactylidae).

The morphological characteristics of the leptodactylid integument of Proceratophrys and Odontophrynus genera were investigated by means of stereoscopic, low vacuum scanning electron and light microscopy. The integument surface of Proceratophrys boiei, Proceratophrys laticeps and Proceratophrys appendiculata exhibited several projections, while the integument of Odontophrynus americanus had rounded elevations with smooth profile. Light microscopic observations showed the basic integument morphology for all anurans, i.e., an epidermis and a dermis, which is subdivided into a spongious layer and a compact layer. The epidermis is formed by basal, intermediary and cornified layers. However, in Proceratophrys genus the cornified layer had an irregular outline, while in O. americanus the external surface was smooth. In the spongious dermis, mucous and venom exocrine glands were observed, but in O. americanus an exclusive glandular type with apocrine secretory pattern was identified. The integument morphology showed peculiar characteristics that may be helpful for genus distinction. Thus, morphological methods may be considered as an efficient means to characterize and to differentiate anuran genera.

Animals↗

PubMed2001

Physiological and morphological characterization of organotypic cocultures of the chick forebrain area MNH and its main input area DMA/DMP.

Cocultures of the learning-relevant forebrain region mediorostral neostriatum and hyperstriatum ventrale (MNH) and its main glutamatergic input area nucleus dorsomedialis anterior thalami/posterior thalami were morphologically and physiologically characterized. Synaptic contacts of thalamic fibers were light- and electron-microscopically detected on MNH neurons by applying the fluorescence tracer DiI-C18(3) into the thalamus part of the coculture. Most thalamic synapses on MNH neurons were symmetric and located on dendritic shafts, but no correlation between Gray-type ultrastructure and dendritic localization was found. Using intracellular current clamp recordings, we found that the electrophysiological properties, such as input resistance, time constant, action potential threshold, amplitude, and duration of MNH neurons, remain stable for over 30 days in vitro. Pharmacological blockade experiments revealed glutamate as the main neurotransmitter of thalamic synapses on MNH neurons, which were also found on inhibitory neurons. High frequency stimulation of thalamic inputs evoked synaptic potentiation in 22% of MNH neurons. The results indicate that DMA/DMP-MNH cocultures, which can be maintained under stable conditions for at least 4 weeks, provide an attractive in vitro model for investigating synaptic plasticity in the avian brain.

Afferent Pathways↗

PubMed1988

Physiological and morphological characterization of striatal neurons transplanted into the striatum of adult rats.

Physiological and morphological properties of transplanted striatal neurons (TSNs) were examined in an in vitro slice preparation. Fetal striatal tissue (E13-14) was implanted as a dissociated cellular suspension into the striatum of adult rats. Intracellular records were obtained from TSNs 2-6 weeks after transplantation. TSNs exhibited biophysical, morphological, and synaptic properties characteristic of normal striatal neurons, despite the disruption involved in processing of the fetal tissue. Differences were observed, however, between the TSNs and host striatal neurons. TSNs consistently had higher input resistance values than host striatal neurons as determined by neuronal responses to intracellular current injection. Stimulation of adjacent host striatum elicited both excitatory and inhibitory postsynaptic potentials in TSNs. By contrast, the same stimuli elicited only excitatory responses in host striatal neurons. Morphologically, TSNs resembled host medium-size spiny neurons as demonstrated by intracellular injection of lucifer yellow. However, the complexity of dendritic branching and the density of spines on the dendrites were less than that observed for host striatal neurons. It was concluded that during the posttransplantation period studied, TSNs possess neuronal properties expected of developmentally immature striatal neurons.

Action Potentials↗

PubMed2002

Genus Coltivirus (family Reoviridae): genomic and morphologic characterization of Old World and New World viruses.

We report a genomic and morphologic study of the European Eyach (EYA) virus (genus Coltivirus, family Reoviridae) and a comparative analysis with the American Colorado tick fever (CTF) virus (the type species of the genus). The previously established, but distant, antigenic relationship between these viruses was strengthened by genetic findings (presence of cognate genes, amino acid identity between 55 and 88%, similar conserved terminal motifs, suspected read-through phenomenon in segment 9 of both viruses) and by indistinguishable ultramicroscopic morphologies. Moreover, putative constitutive modifying enzyme activities were suspected to be carried out by homologous viral proteins (RNA-dependent RNA polymerase, methyl/guanylyl transferase, NTPase). These findings, together with the comparative analysis to genomes of southeast Asian isolates, support the recent classification of arboviruses with 12 segments of dsRNA within two distinct genera (genus Coltivirus and genus Seadornavirus) and raise interesting questions about the evolutionary origins of coltiviruses. The previously proposed hypothesis that EYA virus was derived from an ancestral virus introduced in Europe with the migration of lagomorphs from North-America, would imply a divergence date between American and European isolates of over 50 million years ago (MYA). This analysis allows for the first time to propose an evolutionary rate for virus dsRNA genomes which was found to be in the order of 10(-8) to 10(-9) mutations/nt/year, a rate similar to that of dsDNA genomes.

Americas↗

PubMed1985

Electrophysiological and morphological characterization of neurons in stellate ganglion of cats.

We have studied the general morphology of cat stellate ganglion cells in relation to the synaptic input that each neuron receives. Horseradish peroxidase (HRP) was injected intracellularly into single neurons of the isolated cat stellate ganglia. Neurons of the stellate ganglion receive synaptic information from central and peripheral nerves. Electrical stimulation of the preganglionic nerves (T3 ramus), and postganglionic stimulation of the ventral or dorsal ansa subclavia, evoked graded excitatory responses that led to the discharge of one or more action potentials. The neurons receiving synaptic input from preganglionic and postganglionic nerves have a complex dendritic morphology. These neurons were located close to the postganglionic nerves and had an axon emerging from these nerves. Other neurons located closer to the preganglionic nerves had no identifiable axons leaving the ganglion and could not be excited antidromically by electrical stimulation. These neurons appear to be interneurons. These results indicate that neurons of the cat stellate ganglion are organized in a complex fashion that could be important in the integrative properties of these neurons.

Animals↗

PubMed1989

The morphological characterization and distribution of displaced ganglion cells in the anuran retina.

The number, dendritic morphology, and retinal distribution of displaced ganglion cells were studied in two anuran species, Xenopus laevis and Bufo marinus. Horseradish peroxidase or cobaltic lysine complex was applied to the cut end of the optic nerve, and the size, shape, and retinal position of retrogradely filled ganglion cells displaced into the inner nuclear layer were determined in retinal wholemount and sectioned material. Approximately 1% of ganglion cells in Xenopus and 0.1% in Bufo were found to be displaced. In both species, many of the previously described orthotopic ganglion cell types (Straznicky & Straznicky, 1988; Straznicky et al., 1990) were present among displaced ganglion cells. In Xenopus more displaced ganglion cells were found in the retinal periphery than in the retinal center, and they formed 3 or 4 distinct bands around the optic nerve head. In Bufo the incidence of displaced ganglion cells was higher along the visual streak than in the dorsal and ventral peripheral retina. These results indicate that the distribution of displaced ganglion cells approximates the retinal distribution of orthotopic ganglion cells. One of the likely mechanisms to account for this developmental paradox may be that the formation of the inner plexiform layer, adjacent to the ciliary margin, acts as a mechanical barrier by preventing the entry of some of the late developing ganglion cells into the ganglion cell layer.

Animals↗

PubMed1972

Microsomal lipid peroxidation: morphological characterization.

Lipid peroxidation of liver and kidney microsomes induces a highly characteristic sequence of morphological changes typified by detachment of ribosomes and formation of large aggregates of vesicles bound together by dense amorphous material and myelin figure-like debris. The trilaminar structure of the membrane is, however, retained even after complete peroxidation, though its spacing may be increased. The aggregates resemble lysosomal lipofuscin pigment as well as the membranous aggregates of endoplasmic reticulum seen in the liver after carbon tetrachloride poisoning.

Adenine Nucleotides↗

PubMed2002

Molecular and morphological characterization of Echinococcus granulosus of human and animal origin in Iran.

Iran is an important endemic focus of cystic hydatid disease (CHD) where several species of intermediate host are commonly infected with Echinococcus granulosus. Isolates of E. granulosus were collected from humans and other animals from different geographical areas of Iran and characterized using both DNA (PCR-RFLP of ITS1) and morphological criteria (metacestode rostellar hook dimensions). The sheep and camel strains/genotypes were shown to occur in Iran. The sheep strain was shown to be the most common genotype of E. granulosus affecting sheep, cattle, goats and occasionally camels. The majority of camels were infected with the camel genotype as were 3 of 33 human cases. This is the first time that cases of CHD in humans have been identified in an area where a transmission cycle for the camel genotype exists. In addition, the camel genotype was found to cause infection in both sheep and cattle. Results also demonstrated that both sheep and camel strains can be readily differentiated on the basis of hook morphology alone.

Animals↗

PubMed1985

Interaction of high density lipoproteins with cholesteryl ester-laden macrophages: biochemical and morphological characterization of cell surface receptor binding, endocytosis and resecretion of high density lipoproteins by macrophages.

Morphological and biochemical experiments were carried out to investigate the interaction of human serum high density lipoproteins (HDL) with mouse peritoneal macrophages. It is demonstrated that resident mouse peritoneal macrophages express HDL receptors. Subsequent to receptor-mediated binding, HDL are internalized and intracellularly transported into endosomes. These endosomes do not fuse with the lysosomal compartment but interact with the margin of intracellular plasma lipid droplets. Macrophages do not degrade, but rather resecrete internalized HDL particles as described for the transferrin-receptor pathway. HDL binding to freshly isolated macrophages is saturable at a concentration of approximately 320 ng HDL-protein/mg cell protein and a Scatchard plot indicates the presence of some 130 000-190 000 receptors/cell with a Kd of approximately 9 X 10(-7) M. Binding of HDL on the macrophage surface is significantly enhanced in cholesterol-laden macrophages, whereas the increase in the rate of uptake and secretion is less pronounced. Within the HDL fraction the HDL2 subclass showed higher binding, uptake and secretion activity as compared with HDL3. From these experimental data we postulate that cholesterol uptake from macrophages is mediated by HDL particles which interact with these cells via a receptor-mediated retroendocytosis pathway.

Animals↗

PubMed1979

Morphological characterization of slow and fast pyramidal tract cells in the cat.

In adult cats the morphology of slow and fast pyramidal tract (Pt) neurons was studied following intracellular HRP injections and Golgi impregnation. Both types of neurons are pyramidal cells and their soma are all located in the fifth layer of the motor area. As a rule, fast Pt neurons have large somata and their basal and apical dendrites occupy a larger territory in the tangential plane. In layer I, terminal apical dendrites of fast Pt neurons are smooth and divide poorly while those of slow Pt neurons bear a moderate amount of spines and branch profusely. Midway between the pia and layer V, in the third layer, the apical shafts of both types of Pt cells run upward with little branching. These shafts are more numerous in fast Pt cells (7 to 16) and they are almost devoid of spines. Those of slow Pt cells in layer III number between 5 and 9 and are densely covered with spines. Oblique and horizontal branches of slow and fast Pt neurons extend in layer V and some of them invade the lower part of layer III. It is suggested that this zone corresponds to a true fourth layer in the motor area. In both types of cells oblique and lateral branches bear numerous spines. Within the basal dendritic territory of Pt cells, one has to distinguish two dendritic systems: a short and a long one. The former spreads downward obliquely and appears to remain within layer V. The latter is made up of long descending vertical (antiapical) and oblique dendrites (tap root). While both types of cells may have long antiapical dendrites that run down radially to the lower part of layer VI, tap root dendrites which expand laterally below the cell body for considerable distances are a distinctive feature of fast Pt neurons. Though basal dendrites of all Pt cells bear spines, their number, distribution and shape are very variable in fast Pt cells.

Animals↗

PubMedDate not supplied

[Clinico-morphologic characterization of mucoepidermoid carcinoma of the salivary glands].

64 cases of SGMC were studied. Clinical morphology of epidermoid carcinoma was studied according to the 2nd edition of the International histologic classification of the tumors of this site (WHO, Geneva, 1990). This allows to study not only incidence of this tumor depending on the site, sex and age, but to give new data on its biology. The malignancy of all the three types of this tumor (of low, moderate and high grade) was confirmed by means of histologic, histochemical, electron-microscopic (EM) and EM-histochemical methods. The previous assumption on benign character of the low-grade variant of the tumor was not confirmed.

Adolescent↗

PubMed1986

Isolation and morphological characterization of a mycelial mutant of Candida albicans.

In this paper we describe the isolation of a novel strain of Candida albicans which is a mycelium at ambient temperatures. Mutagenesis of C. albicans ATCC 10261 with N-methyl-N-nitro-N-nitrosoguanidine followed by plating on solid media at 28 degrees C yielded colony morphology variants which were characterized by a raised, rough-surfaced colony of irregular outline in marked contrast to the flat, shiny circular colonies of the parental 10261 strain. One mutant colony, hOG301, was studied in detail. Strain hOG301 was stable and exhibited mycelial morphology over a wide temperature range (5 to 40 degrees C) in several media. The hyphae comprising hOG301 mycelium were examined by light microscopy, scanning electron microscopy, and transmission electron microscopy and showed morphological features described in the literature as being typical of both true hyphae and pseudohyphae. In contrast to 10261, hOG301 was not pathogenic after intraperitoneal injection in mice. This is the first report of a mycelial C. albicans that is stable at ambient temperatures.

Animals↗

PubMed1999

Electrophysiological and morphological characterization of cytochemically-defined neurons in the caudal nucleus of tractus solitarius of the rat.

Morphological and electrophysiological properties of calbindin D-28k-, GABA- and dopamine-beta-hydroxylase-immunopositive neurons were investigated in the caudal nucleus of tractus solitarius of rats, using a patch-clamp whole-cell recording combined with intracellular staining and immunocytochemistry. Calbindin D-28K- and GABA-positive neurons had a small cell body (10.9+/-0.3 microm in diameter) and were distributed throughout the caudal nucleus of tractus solitarius. Double fluorescence immunocytochemistry revealed that calbindin- and GABA-positive neurons formed distinct subpopulations. Calbindin- and GABA-positive neurons double stained for biocytin showed extensive axon collaterals within the nucleus of tractus solitarius and some calbindin-positive, but not GABA-positive neurons, had also projection axons leaving the nucleus of tractus solitarius. Dopamine-beta-hydroxylase-immunopositive neurons had a small (10.8+/-0.3 microm) or large (17.2+/-0.4 microm) cell body. Neurons with a small cell body were observed in the dorsomedial nucleus at the level of the area postrema, and in the area postrema, while neurons with a large cell body were observed in the medial nucleus throughout the caudal nucleus of tractus solitarius. Double fluorescence immunocytochemistry revealed that almost all small dopamine-beta-hydroxylase-positive neurons were also immunoreactive for calbindin, while large dopamine-beta-hydroxylase-positive neurons were not. Double staining for dopamine-beta-hydroxylase and biocytin showed that neurons with a small cell body had moderate axon collaterals. On the contrary, neurons with a large cell body had few, if any, axon collaterals and a projection axon which could leave the nucleus of tractus solitarius. Following stimulation of the tractus solitarius, all neurons with a small cell body exhibited a polysynaptic excitatory response (type I neurons), while dopamine-beta-hydroxylase-immunopositive neurons with a large cell body exhibited a monosynaptic excitatory response (type II neurons) or an excitatory followed by an inhibitory response (type III neurons). Spontaneous and evoked excitatory postsynaptic currents of (type I neurons) calbindin- or GABA-positive neurons were reversibly blocked by 6-cyano-7-nitroquinoxaline-2,3-dione. Spontaneous and evoked inhibitory postsynaptic currents of type III neurons were reversibly blocked by bicuculline. Type II neurons showed no spontaneous excitatory nor inhibitory postsynaptic currents. It was concluded that the three kinds of chemically-defined neurons formed distinct neuronal subpopulations in the caudal nucleus of tractus solitarius in terms of synaptic responses and morphological characteristics such as cell size and axonal trajectory.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed1993

Morphological characterization of adult Echinococcus granulosus as a means of determining transmission patterns.

Host induced changes in morphological characters of the rostellar hooks of Echinococcus granulosus were used to determine the origin of infection in definitive hosts in rural areas of southeastern Australia where wild and domestic cycles of transmission may interact. The morphological characters studied vary depending on the species of intermediate host (macropod marsupials, sheep) in which protoscoleces develop, and these characters are retained in adult worms. It was therefore possible to determine whether definitive hosts (dingoes and foxes) acquired infection by consuming protoscoleces of E. granulosus from macropods or from sheep. The results correlated well with the known distribution of intermediate hosts and illustrate the practical value of such morphological markers in epidemiological studies.

Animals↗

PubMed1986

Physicochemical and morphological characterization of polyisobutyl cyanoacrylate nanocapsules.

Two different polymerization mechanisms of alkyl cyanoacrylates were compared with regard to their morphological and physico-chemical characteristics. Cyanoacrylates were polymerized by simple emulsification into an aqueous medium or by interfacial polymerization in an o/w type emulsion. Suspensions of particles obtained by these two mechanisms show dramatic differences when studied for their turbidity, refractive index, and stability following centrifugation. These observations are consistent with the fact that nanoparticles obtained by emulsion polymerization are known to be formed by a full polymer core, while nanocapsules obtained by interfacial polymerization were thought to consist of an internal oil droplet surrounded by a polymeric wall. This theory was further confirmed by an electron microscopic examination of the internal structures of the two types of polymeric aggregates.

Capsules↗

PubMed1985

Morphological characterization of the Serratia marcescens bacteriophage SLP.

SLP is a lambda-like bacteriophage specific for Serratia marcescens strains. Morphological studies have demonstrated that SLP virions present two cross-bar structures on its tail not described in bacteriophages specific for Enterobacteriaceae. SDS-polyacrylamide gel electrophoresis of major capsid proteins as well as electron micrographs are reported.

Bacteriophages↗